Sounding reference signal triggering for enhanced carrier aggregation

ABSTRACT

Methods, systems, and devices for wireless communication are described. A method at a user equipment (UE) includes receiving signaling that indicates a carrier aggregation (CA) configuration (having carriers configured for UL and downlink (DL) data transmissions) and an auxiliary uplink (UL) configuration (having carriers configured for UL reference signal transmissions). The method also includes receiving a resource assignment on a DL carrier of the CA configuration, and transmitting an aperiodic sounding reference signal (A-SRS) using the one or more carriers of the auxiliary UL configuration based at least in part on the received resource assignment. Another method is performed by a UE having a CA configuration and an A-SRS configuration, including receiving a resource assignment on a DL carrier in the CA configuration, detecting a trigger for transmitting an A-SRS, determining UL resources of the A-SRS configuration for transmitting the A-SRS, and transmitting the A-SRS on the determined UL resources.

CROSS REFERENCES

The present application for patent is a Continuation of U.S. patentapplication Ser. No. 15/474,840 by Rico Alvarino, et al., entitled“Sounding Reference Signal Triggering For Enhanced Carrier Aggregation”filed Mar. 30, 2017, which claims priority to U.S. Provisional PatentApplication No. 62/317,465 by Rico Alvarino, et al., entitled “SoundingReference Signal Triggering For enhanced Carrier Aggregation,” filedApr. 1, 2016, assigned to the assignee hereof.

BACKGROUND

The following relates generally to wireless communication, and morespecifically to sounding reference signal (SRS) triggering for enhancedcarrier aggregation (eCA).

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., time, frequency, and power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, and orthogonal frequencydivision multiple access (OFDMA) systems. A wireless multiple-accesscommunications system may include a number of base stations, eachsimultaneously supporting communication for multiple communicationdevices, which may each be referred to as a user equipment (UE).

A wireless communication system may support multiple component carriers(CCs) in a carrier aggregation (CA) or enhanced carrier aggregation (ECAor eCA) configuration. CCs may be configured for uplink (UL) anddownlink (DL) communication between a base station and a UE. A UE maytransmit reference signals (e.g., sounding reference signals (SRS)) toindicate the quality of a frequency channel used for communication witha base station. Other, unconfigured UL CCs could possibly be used forSRS transmissions, but aperiodic SRS transmissions are typicallytriggered with a grant of UL resources for data transmissions on thesame CC as the SRS.

SUMMARY

Methods, systems, and devices for wireless communication that supportaperiodic sounding reference signal (A-SRS) triggering for enhancedcarrier aggregation (eCA). A user equipment (UE) may receive signalingthat indicates a carrier aggregation (CA) configuration (having carriersconfigured for UL and DL data transmissions) and an auxiliary ULconfiguration (having carriers configured for UL reference signaltransmissions). A resource assignment on a DL carrier of the CAconfiguration may be received, and the UE may transmit an A-SRS usingthe one or more carriers of the auxiliary UL configuration based atleast in part on the received resource assignment.

A base station may transmit signaling that indicates a CA configurationand an auxiliary UL configuration for a UE. The CA configuration mayhave carriers configured for UL and DL data transmissions, and theauxiliary UL configuration may have carriers configured for UL referencesignal transmissions. The base station then transmits a resourceassignment on a DL carrier to the one or more carriers of the CAconfiguration, and receives back from the UE an A-SRS in the one or morecarriers of the auxiliary UL configuration in response to thetransmitted resource assignment. A UE may also have a CA configurationand an A-SRS configuration, and receive a resource assignment on a DLcarrier in the CA configuration, detect a trigger for transmitting anA-SRS, determine UL resources of the A-SRS configuration fortransmitting the A-SRS, and transmit the A-SRS on the determined ULresources.

A method of wireless communication is described. The method may includeidentifying a carrier aggregation (CA) configuration and an aperiodicsounding reference signal (A-SRS) configuration of the UE, wherein theA-SRS configuration comprises one or more component carriers (CCs) onwhich the UE does not perform uplink (UL) data transmissions, receivinga resource assignment on a downlink (DL) CC in the CA configuration,detecting a trigger for transmitting one or more A-SRS transmissionsbased at least in part on a downlink control information (DCI) format ofthe resource assignment, determining one or more CCs of the A-SRSconfiguration for transmitting the one or more A-SRS transmissions basedat least in part on the DCI format of the resource assignment, andtransmitting the one or more A-SRS transmissions on the one or moredetermined CCs of the A-SRS configuration.

An apparatus for wireless communication is described. The apparatus mayinclude means for identifying a carrier aggregation (CA) configurationand an aperiodic sounding reference signal (A-SRS) configuration of theUE, wherein the A-SRS configuration comprises one or more componentcarriers (CCs) on which the UE does not perform uplink (UL) datatransmissions, means for receiving a resource assignment on a downlink(DL) CC in the CA configuration, means for detecting a trigger fortransmitting one or more A-SRS transmissions based at least in part on adownlink control information (DCI) format of the resource assignment,means for determining one or more CCs of the A-SRS configuration fortransmitting the one or more A-SRS transmissions based at least in parton the DCI format of the resource assignment, and means for transmittingthe one or more A-SRS transmissions on the one or more determined CCs ofthe A-SRS configuration.

Another apparatus for wireless communication is described. The apparatusmay include a processor, memory in electronic communication with theprocessor, and instructions stored in the memory. The instructions maybe operable to cause the processor to identify a carrier aggregation(CA) configuration and an aperiodic sounding reference signal (A-SRS)configuration of the UE, wherein the A-SRS configuration comprises oneor more component carriers (CCs) on which the UE does not perform uplink(UL) data transmissions, receive a resource assignment on a downlink(DL) CC in the CA configuration, detect a trigger for transmitting oneor more A-SRS transmissions based at least in part on a downlink controlinformation (DCI) format of the resource assignment, determine one ormore CCs of the A-SRS configuration for transmitting the one or moreA-SRS transmissions based at least in part on the DCI format of theresource assignment, and transmit the one or more A-SRS transmissions onthe one or more determined CCs of the A-SRS configuration.

A non-transitory computer readable medium for wireless communication isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to identify a carrieraggregation (CA) configuration and an aperiodic sounding referencesignal (A-SRS) configuration of the UE, wherein the A-SRS configurationcomprises one or more component carriers (CCs) on which the UE does notperform uplink (UL) data transmissions, receive a resource assignment ona downlink (DL) CC in the CA configuration, detect a trigger fortransmitting one or more A-SRS transmissions based at least in part on adownlink control information (DCI) format of the resource assignment,determine one or more CCs of the A-SRS configuration for transmittingthe one or more A-SRS transmissions based at least in part on the DCIformat of the resource assignment, and transmit the one or more A-SRStransmissions on the one or more determined CCs of the A-SRSconfiguration.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, one or more of the CCs of theA-SRS configuration comprise one or more auxiliary UL CCs, the one ormore auxiliary UL CCs being configured for UL reference signaltransmissions and not configured for UL data transmissions.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, receiving the resourceassignment comprises: identifying power control information in a fieldof the DCI format that indicates an A-SRS transmitter power control(TPC) command, wherein the one or more A-SRS transmissions may betransmitted using a transmit power based at least in part on the powercontrol information.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for identifying the one or more CCs ofthe A-SRS configuration based at least in part on a plurality of bits ofthe resource assignment configured according to the DCI format.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the resource assignmentcomprises a sounding reference signal radio network temporary identifier(SRS-RNTI), wherein the SRS-RNTI triggers a plurality of A-SRStransmissions in a plurality of UL resources of the A-SRS configuration.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for identifying additional uplinktransmissions to be transmitted simultaneously with the one or moreA-SRS transmissions. Some examples of the method, apparatus, andnon-transitory computer-readable medium described above may furtherinclude processes, features, means, or instructions for determiningwhether to transmit the additional uplink transmissions or the one ormore A-SRS transmissions, or both, based at least in part on aprioritization.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for transmitting the one or more A-SRStransmissions may be based at least in part on determining to transmitthe one or more A-SRS transmissions according to the prioritization.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for identifying additional uplinktransmissions to be transmitted simultaneously with the one or moreA-SRS transmissions. Some examples of the method, apparatus, andnon-transitory computer-readable medium described above may furtherinclude processes, features, means, or instructions for transmitting theone or more A-SRS transmissions instead of the additional uplinktransmissions, wherein the additional uplink transmissions comprise aphysical uplink shared channel (PUSCH) transmission on one or morecomponent carriers of the CA configuration.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, a DL carrier of the CAconfiguration and one of the one or more CCs of the A-SRS configurationshare frequency resources.

A method of wireless communication is described. The method may includeidentifying a carrier aggregation (CA) configuration and an aperiodicsounding reference signal (A-SRS) configuration of one or more userequipments (UEs), wherein the A-SRS configuration comprises one or morecomponent carriers (CCs) on which the one or more UEs do not performuplink (UL) data transmissions, transmitting a resource assignment on adownlink (DL) CC in the CA configuration, the resource assignmentcomprising a trigger for one or more UEs to transmit one or more A-SRStransmissions based at least in part on a downlink control information(DCI) format of the resource assignment, wherein one or more CCs of theA-SRS configuration for transmitting the one or more A-SRS transmissionsare identified based at least in part on the DCI format of the resourceassignment, and receiving A-SRS transmissions from the one or more UEson CCs identified by the DCI format.

An apparatus for wireless communication is described. The apparatus mayinclude means for identifying a carrier aggregation (CA) configurationand an aperiodic sounding reference signal (A-SRS) configuration of oneor more user equipments (UEs), wherein the A-SRS configuration comprisesone or more component carriers (CCs) on which the one or more UEs do notperform uplink (UL) data transmissions, means for transmitting aresource assignment on a downlink (DL) CC in the CA configuration, theresource assignment comprising a trigger for one or more UEs to transmitone or more A-SRS transmissions based at least in part on a downlinkcontrol information (DCI) format of the resource assignment, wherein oneor more CCs of the A-SRS configuration for transmitting the one or moreA-SRS transmissions are identified based at least in part on the DCIformat of the resource assignment, and means for receiving A-SRStransmissions from the one or more UEs on CCs identified by the DCIformat.

Another apparatus for wireless communication is described. The apparatusmay include a processor, memory in electronic communication with theprocessor, and instructions stored in the memory. The instructions maybe operable to cause the processor to identify a carrier aggregation(CA) configuration and an aperiodic sounding reference signal (A-SRS)configuration of one or more user equipments (UEs), wherein the A-SRSconfiguration comprises one or more component carriers (CCs) on whichthe one or more UEs do not perform uplink (UL) data transmissions,transmit a resource assignment on a downlink (DL) CC in the CAconfiguration, the resource assignment comprising a trigger for one ormore UEs to transmit one or more A-SRS transmissions based at least inpart on a downlink control information (DCI) format of the resourceassignment, wherein one or more CCs of the A-SRS configuration fortransmitting the one or more A-SRS transmissions are identified based atleast in part on the DCI format of the resource assignment, and receiveA-SRS transmissions from the one or more UEs on CCs identified by theDCI format.

A non-transitory computer readable medium for wireless communication isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to identify a carrieraggregation (CA) configuration and an aperiodic sounding referencesignal (A-SRS) configuration of one or more user equipments (UEs),wherein the A-SRS configuration comprises one or more component carriers(CCs) on which the one or more UEs do not perform uplink (UL) datatransmissions, transmit a resource assignment on a downlink (DL) CC inthe CA configuration, the resource assignment comprising a trigger forone or more UEs to transmit one or more A-SRS transmissions based atleast in part on a downlink control information (DCI) format of theresource assignment, wherein one or more CCs of the A-SRS configurationfor transmitting the one or more A-SRS transmissions are identifiedbased at least in part on the DCI format of the resource assignment, andreceive A-SRS transmissions from the one or more UEs on CCs identifiedby the DCI format.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the one or more CCs of theA-SRS configuration comprise one or more auxiliary UL CCs, the one ormore auxiliary UL CCs being configured for UL reference signaltransmissions and not configured for UL data transmissions.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for transmitting power controlinformation in a field of the DCI format that indicates an A-SRStransmitter power control (TPC) command.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the one or more CCs of theA-SRS configuration may be identified based at least in part on aplurality of bits of the resource assignment configured according to theDCI format.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the resource assignmentcomprises a sounding reference signal radio network temporary identifier(SRS-RNTI), wherein the SRS-RNTI triggers a plurality of A-SRStransmissions in a plurality of UL resources of the A-SRS configuration.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, a DL carrier of the CAconfiguration and one of the one or more CCs of the A-SRS configurationshare frequency resources.

In one embodiment, a device or system may include a processor, memory inelectronic communication with the processor, instructions stored in thememory and operable, when executed by the processor, to cause the mobiledevice to: identify a carrier aggregation (CA) configuration and anaperiodic sounding reference signal (A-SRS) configuration of the mobiledevice, wherein the A-SRS configuration comprises one or more componentcarriers (CCs) on which the mobile device does not perform uplink (UL)data transmissions, receive a resource assignment on a downlink (DL) CCin the CA configuration, detect a trigger for transmitting one or moreA-SRS transmissions based at least in part on a downlink controlinformation (DCI) format of the resource assignment, determine one ormore CCs of the A-SRS configuration for transmitting the one or moreA-SRS transmissions based at least in part on the DCI format of theresource assignment, and transmit the one or more A-SRS transmissions onthe one or more determined CCs of the A-SRS configuration.

Some examples of the device or system described above may also includeone or more of the CCs of the A-SRS configuration comprise one or moreauxiliary UL CCs, the one or more auxiliary UL CCs being configured forUL reference signal transmissions and not configured for UL datatransmissions.

In some examples of the undefined described above, the instructions maybe executable by the processor to cause the mobile device to: identifypower control information in a field of the DCI format that indicates anA-SRS transmitter power control (TPC) command. Some examples of thesystem described above may also include transmitting the one or moreA-SRS transmissions using a transmit power based at least in part on thepower control information.

In some examples of the device or system described above, theinstructions may be executable by the processor to cause the mobiledevice to: identify the one or more CCs of the A-SRS configuration basedat least in part on a plurality of bits of the resource assignmentconfigured according to the DCI format.

In some examples of the device or system described above, the resourceassignment comprises a sounding reference signal radio network temporaryidentifier (SRS-RNTI), wherein the SRS-RNTI triggers a plurality ofA-SRS transmissions in a plurality of UL resources of the A-SRSconfiguration.

In some examples of the device or system described above, theinstructions may be executable by the processor to cause the mobiledevice to: identify additional uplink transmissions to be transmittedsimultaneously with the one or more A-SRS transmissions. Some examplesof the device or system described above may also include determiningwhether to transmit the additional uplink transmissions or the one ormore A-SRS transmissions, or both, based at least in part on aprioritization.

In some examples of the undefined described above, the instructions maybe executable by the processor to cause the mobile device to: transmitthe one or more A-SRS transmissions based at least in part ondetermining to transmit the one or more A-SRS transmissions according tothe prioritization.

In some examples of the device or system described above, theinstructions may be executable by the processor to cause the mobiledevice to: identify additional uplink transmissions to be transmittedsimultaneously with the one or more A-SRS transmissions. Some examplesof the device or system described above may also include transmittingthe one or more A-SRS transmissions instead of the additional uplinktransmissions, wherein the additional uplink transmissions comprise aphysical uplink shared channel (PUSCH) transmission on one or morecomponent carriers of the CA configuration.

Some examples of the device or system described above may also include aDL carrier of the CA configuration and one of the one or more CCs of theA-SRS configuration share frequency resources.

In one embodiment, a device or system may include a processor, memory inelectronic communication with the processor, instructions stored in thememory and operable, when executed by the processor, to cause thenetwork device to: identify a carrier aggregation (CA) configuration andan aperiodic sounding reference signal (A-SRS) configuration of one ormore user equipments (UEs), wherein the A-SRS configuration comprisesone or more component carriers (CCs) on which the one or more UEs do notperform uplink (UL) data transmissions, transmit a resource assignmenton a downlink CC in the CA configuration, the resource assignmentcomprising a trigger for one or more UEs to transmit one or more A-SRStransmissions based at least in part on a downlink control information(DCI) format of the resource assignment, wherein one or more CCs of theA-SRS configuration for transmitting the one or more A-SRS transmissionsare identified based at least in part on the DCI format of the resourceassignment, and receive A-SRS transmissions from the one or more UEs onCCs identified by the DCI format.

In some examples of the device or system described above, the one ormore CCs of the A-SRS configuration comprise one or more auxiliary ULCCs, the one or more auxiliary UL CCs being configured for UL referencesignal transmissions and not configured for UL data transmissions.

In some examples of the undefined described above, the instructions maybe executable by the processor to cause the network device to: transmitpower control information in a field of the DCI format that indicates anA-SRS transmitter power control (TPC) command.

In some examples of the device or system described above, the one ormore CCs of the A-SRS configuration may be identified based at least inpart on a plurality of bits of the resource assignment configuredaccording to the DCI format.

In some examples of the device or system described above, the resourceassignment comprises a sounding reference signal radio network temporaryidentifier (SRS-RNTI), wherein the SRS-RNTI triggers a plurality ofA-SRS transmissions in a plurality of UL resources of the A-SRSconfiguration.

Some examples of the device or system described above may also include aDL carrier of the CA configuration and one of the one or more CCs of theA-SRS configuration share frequency resources.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communications system thatsupports aperiodic sounding reference signal (A-SRS) triggering forenhanced carrier aggregation (eCA) in accordance with aspects of thepresent disclosure;

FIG. 2 illustrates an example of a wireless communications system thatsupports A-SRS triggering for eCA in accordance with aspects of thepresent disclosure;

FIG. 3 illustrates an example of a CC configuration that supports A-SRStriggering for eCA in accordance with aspects of the present disclosure;

FIG. 4 illustrates an example of a process flow in a system thatsupports A-SRS triggering for eCA in accordance with aspects of thepresent disclosure;

FIG. 5 illustrates an example of a process flow in a system thatsupports A-SRS triggering for eCA in accordance with aspects of thepresent disclosure;

FIGS. 6 through 8 show block diagrams of a wireless device that supportsA-SRS triggering for eCA in accordance with aspects of the presentdisclosure;

FIG. 9 illustrates a block diagram of a system including a UE thatsupports A-SRS triggering for eCA in accordance with aspects of thepresent disclosure;

FIGS. 10 through 12 show block diagrams of a wireless device thatsupports A-SRS triggering for eCA in accordance with aspects of thepresent disclosure;

FIG. 13 illustrates a block diagram of a system including a base stationthat supports A-SRS triggering for eCA in accordance with aspects of thepresent disclosure; and

FIGS. 14 through 22 illustrate methods for A-SRS triggering for eCA inaccordance with aspects of the present disclosure.

DETAILED DESCRIPTION

Aperiodic sounding reference signals (A-SRS) may be triggered onotherwise unconfigured UL CCs in grants for resources of other carriersor with specific requests for A-SRS on the UL CC. This may leverage a UEcapability to transmit on multiple UL carriers and may provideadditional opportunities for SRS transmission. This may address issuesof inefficient resource allocation or other causes of reducedthroughput.

For example, wireless communication systems may configure a portion ofUL CCs that a UE is capable of supporting and may reserve soundingreference signals (SRS) transmissions for uplink CCs that are availablefor CA. This may result in an inaccurate estimation of channelconditions for bands that do not have an UL CC configured, which maycause inefficient use of the channel and reduced throughput. In someimplementations of a wireless communications systems (e.g., legacy LTE),sounding reference signals (SRS) may be transmitted from a UE to a basestation on an UL (e.g., to enable the base station to perform channelsounding). SRS may be transmitted periodically or aperiodically. Forperiodic SRS, a radio resource control (RRC) message may be received bythe UE and indicate that a UE is to periodically transmit the periodicSRS to its serving base station (BS). For aperiodic SRS (A-SRS), an ULor DL grant may be sent by a serving BS to a UE to trigger thetransmission of the A-SRS. However, while some DL control information(DCI) formats associated with legacy LTE may support a trigger of anA-SRS (e.g., DCI formats 1A, 2B, 2C, 2D), and UL DCI formats alsosupport triggers for A-SRS (e.g., DCI formats 0, 4), other DCI formatsdo not, and in particular the other DCI formats for DL grants. Thus,even if a UE is configured by a base station to transmit an A-SRS on anUL CC to the BS, techniques to trigger the transmission of the A-SRS areneeded for some DCI formats.

Furthermore, where a UE is configured to receive on multiple DL CCs(e.g., including one or more CCs dedicated for DL), but transmit on asmall number (e.g., one) UL CCs, the UE may not monitor UL grants forthe DL CCs, and in particular for those DL CCs that do not share theirfrequency with an UL CC (e.g. the dedicated DL CCs). Thus, the UE maynot be able to rely on monitoring an UL grant to receive a trigger foran A-SRS. Triggering of A-SRS may be based on modified DL grants,modified UL grants, group triggers that are dedicated per UE of thegroup, and triggers that are dedicated per group of UEs. Each of theseexamples of triggering of A-SRS will be further discussed in detailbelow.

In other examples, where there are many DL CCs in a particular CAconfiguration, there may be collisions between multiple A-SRSs orbetween one or more A-SRSs and other UL signals to be transmitted on anUL CC (e.g., periodic SRS, PUSCH, PUCCH containing HARQ, PUCCHcontaining CSI feedback, dynamically-scheduled PUSCH, SPS PUSCH, etc.).Thus, a predetermined and/or configurable hierarchy of UL signals may beused to resolve such collisions.

Aspects of the disclosure introduced above are described below in thecontext of a wireless communication system. Aspects of the disclosureare further illustrated by and described with reference to apparatusdiagrams, system diagrams, and flowcharts that relate to A-SRStriggering for eCA.

FIG. 1 illustrates an example of a wireless communications system 100 inaccordance with various aspects of the present disclosure. The wirelesscommunications system 100 includes base stations 105, UEs 115, and acore network 130. In some examples, the wireless communications system100 may be a Long Term Evolution (LTE)/LTE-Advanced (LTE-A) network.

Base stations 105 may wirelessly communicate with UEs 115 via one ormore base station antennas. Each base station 105 may providecommunication coverage for a respective geographic coverage area 110.Communication links 125 shown in wireless communications system 100 mayinclude UL transmissions from a UE 115 to a base station 105, or DLtransmissions, from a base station 105 to a UE 115. UEs 115 may bedispersed throughout the wireless communications system 100, and each UE115 may be stationary or mobile. A UE 115 may also be referred to as amobile station, a subscriber station, a remote unit, a wireless device,an access terminal (AT), a handset, a user agent, a client, or liketerminology. A UE 115 may also be a cellular phone, a wireless modem, ahandheld device, a personal computer, a tablet, a personal electronicdevice, an machine type communication (MTC) device, etc.

Base stations 105 may communicate with the core network 130 and with oneanother. For example, base stations 105 may interface with the corenetwork 130 through backhaul links 132 (e.g., S1, etc.). Base stations105 may communicate with one another over backhaul links 134 (e.g., X2,etc.) either directly or indirectly (e.g., through core network 130).Base stations 105 may perform radio configuration and scheduling forcommunication with UEs 115, or may operate under the control of a basestation controller (not shown). In some examples, base stations 105 maybe macro cells, small cells, hot spots, or the like. Base stations 105may also be referred to as eNodeBs (eNBs) 105.

A sounding reference signal (SRS) may be transmitted by UE 115 using apredetermined sequence (e.g., a Zadoff-Chu sequence) so that a basestation 105 may estimate the UL channel quality. An A-SRS transmissionmay not be associated with transmission of data on another channel, andmay be transmitted periodically on a wide bandwidth (e.g., a bandwidthincluding more subcarriers than are allocated for UL data transmission).An SRS may also be scheduled on multiple antenna ports and may still beconsidered a single SRS transmission. An SRS transmission may becategorized as a Type 0 (periodically transmitted at equally spacedintervals) SRS or as a Type 1 (aperiodic) SRS. Thus, data gathered by abase station 105 from an SRS may be used to inform an UL scheduler. Abase station 105 may also utilize an SRS to check timing alignmentstatus and send time alignment commands to the UE 155-a.

A user equipment (UE) 115 may be configured with a number of componentcarriers (CCs) (e.g., up to 32 CCs) for carrier aggregation (CA). TheCCs of a CA may be associated with one or several base stations 105.Each CC may be backward compatible and span a different frequency gap(e.g., up to 20 MHz). Multiple CCs configured for a UE 115 may span amaximum frequency region (e.g., up to 640 MHz). CCs in CA may be allfrequency division duplex (FDD), all time division duplex (TDD), or amixture of FDD and TDD. Different TDD CCs may have the same or differentuplink (UL)/downlink (DL) configurations. In some cases, specialsubframes may be configured differently for different TDD CCs. One CCmay be configured as the UE's primary CC (e.g., PCell or PCC) and otherCCs may be configured as secondary CCs (e.g., SCell or SCC). The PCellmay carry a physical uplink control channel (PUCCH). Some CCs may be ona licensed spectrum, while some other CCs may be on an unlicensedspectrum or a shared spectrum.

In some examples, UEs 115 may be configured with a large number of CCs(e.g., 20 or more CCs). This type of configuration may be referred to asenhanced CA (eCA). The term eCA may also refer to CA configurations thatare enhanced relative to earlier deployments of CA-aggregation schemes.For example, use of auxiliary UL CCs or dynamically switching betweenCCs for certain transmissions may be examples of eCA. The terms CA andeCA may thus be used interchangeably to describe features related tomulti-carrier configurations. In some cases, eCA may refer to CA inenhanced systems.

In some cases, a UE 115 may be served by cells from two or more basestations 105 that are connected by a non-ideal backhaul links 134 indual connectivity operation. For example, the connection between theserving base stations 105 may not be sufficient to facilitate precisetiming coordination. Thus, in some cases, the cells serving a UE 115 maybe divided into multiple TAGs. In another example, one or more CCs maybe connected with a one or more repeaters, while other CCs may beoperated without a repeater. As a result, in some cases, the cells ordifferent CCs serving a UE 115 may be divided into multiple TAGs. EachTAG may be associated with a different timing offset, such that the UE115 may synchronize UL transmissions differently for different ULcarriers.

In dual-connectivity, cells may be partitioned into two groups, theprimary cell group (PCG) and the secondary cell group (SCG). Each groupmay have one or more cells in CA and may use a single cell to carryPUCCH. So in some cases, a UE may be configured with a PCell and anotherCC may be configured as the primary secondary CC (e.g., PSCell). APSCell may also carry PUCCH (e.g., for the SCG) but may not include allof the attributes of the PCell. UL control information may be separatelyconveyed to each group via the PUCCH in each group. An SCG may alsosupport semi-persistent scheduling (SPS) and scheduling requests (SRs).A UE 115 may additionally monitor a common search space in SCG.

In some cases, wireless communications system 100 may utilize enhancedcomponent carriers. An eCC may be characterized by one or more featuresincluding: wider bandwidth, shorter symbol duration, shortertransmission time interval (TTIs), and modified control channelconfiguration. In some cases, an eCC may be associated with a carrieraggregation configuration or a dual connectivity configuration (e.g.,when multiple serving cells have a suboptimal or non-ideal backhaullink). An eCC may also be configured for use in unlicensed spectrum orshared spectrum (where more than one operator is allowed to use thespectrum). An eCC characterized by wide bandwidth may include one ormore segments that may be utilized by UEs 115 that are not capable ofmonitoring the whole bandwidth or prefer to use a limited bandwidth(e.g., to conserve power).

In some cases, an eCC may utilize a different symbol duration than otherCCs, which may include use of a reduced symbol duration as compared withsymbol durations of the other CCs. A shorter symbol duration isassociated with increased subcarrier spacing. A device, such as a UE 115or base station 105, utilizing eCCs may transmit wideband signals (e.g.,20, 40, 60, 80 MHz, etc.) at reduced symbol durations (e.g., 16.67microseconds). A TTI in eCC may consist of one or multiple symbols. Insome cases, the TTI duration (that is, the number of symbols in a TTI)may be variable. In some cases, an eCC may utilize a different symbolduration than other CCs, which may include use of a reduced symbolduration as compared with symbol durations of the other CCs. A shortersymbol duration is associated with increased subcarrier spacing. Adevice, such as a UE 115 or base station 105, utilizing eCCs maytransmit wideband signals (e.g., 20, 40, 60, 80 MHz, etc.) at reducedsymbol durations (e.g., 16.67 microseconds). A TTI in eCC may consist ofone or multiple symbols. In some cases, the TTI duration (that is, thenumber of symbols in a TTI) may be variable.

In some implementations of a wireless communications systems 100 (e.g.,legacy LTE), sounding reference signals (SRS) may be transmitted from aUE 115 to a base station 105 on an uplink (UL) (e.g., to enable the basestation to perform channel sounding). SRS may be transmittedperiodically or aperiodically. For aperiodic SRS (A-SRS), an UL or DLgrant may be sent by a serving BS to a UE to trigger the transmission ofthe A-SRS. Triggering of A-SRS may be based on modified DL grants,modified UL grants, group triggers that are dedicated per UE of thegroup, and triggers that are dedicated per group of UEs. Each of theseexamples of triggering of A-SRS will be further discussed in detailbelow. In other examples, there may be collisions between multipleA-SRSs or between one or more A-SRSs and other UL signals to betransmitted on an UL CC (e.g., periodic SRS, PUSCH, PUCCH containingHARQ, PUCCH containing CSI feedback, dynamically-scheduled PUSCH, SPSPUSCH, etc.). Thus, a predetermined and/or configurable hierarchy of ULsignals may be used to resolve such collisions.

FIG. 2 illustrates an example of a wireless communications system 200for A-SRS triggering for CA. Wireless communications system 200 mayinclude base station 105-a and UE 115-a, which may be examples of thecorresponding devices described with reference to FIG. 1. Wirelesscommunications system 200 represents a system that supportsconfiguration of auxiliary UL CCs 215 for transmission of A-SRS.Configuration of auxiliary UL CCs 215 may be based on a UE's CC supportcapabilities in CA.

In some cases, a CA configuration may include more DL CCs 205 than ULCCs 210. This may be known as an asymmetric CA configuration. Forexample, a UE 115 (e.g., UE 115-a) may not transmit A-SRS for channelestimation of DL CCs 205 that do not have corresponding UL CCs. In suchcases, the serving base station 105 (e.g., base station 105-a) may notbe able to produce accurate channel estimates for all of the DL CCs 205.So, base station 105-a may configure UE 115-a with a number of auxiliaryUL CCs 215 for transmission of A-SRS (e.g., corresponding to the numberof DL CCs 205 that are not associated with an UL CC 210 of the CAconfiguration). This may enable more accurate channel estimation foreach CC in the CA configuration and may improve the efficiency of thewireless communications system 200.

UE 115-a may transmit A-SRS on available resources of auxiliary UL CCs215 which may otherwise not be configured for UL data transmissions. Insome cases, a UE 115 may transmit using auxiliary UL CCs 215 in parallel(e.g., concurrently) with other UL CCs in a CA configuration (e.g., CAUL CC 210). UEs 115 that do not support parallel transmissions maytransmit A-SRS on auxiliary UL CCs 215 with coordinated antennaswitching, rate matching, or resource puncturing procedures, in variousexamples. In some cases, UE 115 may transmit on auxiliary UL CC 215 andUL CC 210 at different times, and may indicate a time or gap associatedwith tuning between the carriers. For example, a gap duration may beindicated to coordinate a time duration for switching to and from UL CCswith base station 105-a (e.g., time duration associated with switchingbetween auxiliary UL CCs 215 and CA UL CCs 210).

Auxiliary UL CCs 215 may be configured and/or operated based on a UL CCcapability of a UE 115. Different UEs 115 may have differentcapabilities in UL CA. For example, UE 115-a may be capable of two ULCCs (e.g., configured with one auxiliary UL CC 215 and one CA UL CC 210)and UE 115-b may be capable of using three UL CCs (e.g., configured withtwo auxiliary UL CCs 215 and one CA UL CC 210). UE capability may dependon the frequency band. That is, a UE 115 may be capable of UL CA forcertain bands, but not capable of UL CA with other bands. A UE 115 thatsupports a CA configuration with a certain number of UL CCs (e.g., NCCs) may be configured with fewer than that number of CCs (e.g., lessthan N CCs). For example, UE 115-a may be capable of using UL CCs 210 ina CA configuration, but it may be configured with one UL CC 210 for theCA configuration.

By way of example, UE 115-b may be configured with three DL CCs 205 andone UL CC 210 for CA, even though UE 115-b may be capable of supportinga CA configuration with three UL CCs 210. In some examples, a UE 115-bmay be limited to parallel transmissions based on a total number ofconfigured UL CCs. For example, UE 115-b may be configured with a CAconfiguration that includes two UL CCs 210 and it may be configured withone auxiliary UL CC 215, and UE 115-b may be limited to concurrenttransmission on two UL CCs during a single subframe. But in some cases,a UE 115-b may make parallel UL transmissions based on a total number ofCCs UE 115-b supports. For example, UE 115-b may support a CAconfiguration with three UL CCs 210, and the UE 115-b may be configuredwith two UL CCs 210 and one auxiliary UL CC 215. In such case, UE 115-bmay concurrently transmit on both UL CCs 210 and the auxiliary UL CC 215during a single subframe.

For UEs 115 that are not capable of parallel transmissions for two ormore CCs involved in switching, UL CCs may be configured based on the ULCCs symbol availability. Depending on the time required to switch fromone CC to another CC, some symbols may be punctured or rate matchedaround to facilitate the switching (e.g., the first symbol of an ULsubframe). For example, UE 115-b may switch from an auxiliary UL CC 215(e.g., a CC configured for reference signal transmission) to a UL CC 210(e.g., a CC configured for UL control and data transmissions). In suchcases, in order to facilitate the switching, first symbol of a subframeused for transmission on the UL CC 210 may not be available for ULtransmissions (e.g., PUSCH or PUCCH). Alternatively, UE 115-b may switchfrom a UL CC 210 to an auxiliary UL CC 215. This type of switchingscenario may not affect other transmissions. For example, in a subframeused for A-SRS transmission on an auxiliary UL CC 215, there may be noother transmission in at least the first several symbols of thatsubframe. So there may be little or, no impact on the auxiliary UL CC215.

The UE capability may affect the extent to which symbols used for othertransmissions may be affected by switching between CCs. If a UE 115 iscapable of fast switching, the UE 115 may switch between CCs withoutaffecting other transmissions and so there may be no symbol designatedfor switching. Further, A-SRS symbol location may affect the extent towhich transmission in other symbols may be impacted. For example, if anA-SRS is not located in the last symbol or the last set of symbols of asubframe, other symbols may not be affected due to a UE 115 switchingbetween CCs. Therefore it may be unnecessary for wireless communicationsystem 200 to facilitate switching impacts on specific symbols.

In some cases, a UE 115 may indicate certain requirements or preferencesfor scheduling to accommodate switching. For example, a UE 115 maysignal a time duration or gap during which a UE 115 needs or preferablyhas to switch from one CC to another. The gap may depend on thefrequency bands of the CCs between which the UE 115 is switching. By wayof example, for inter-band switching, a UE 115 may signal for a certainband combination whether a short or long gap is used for switching(e.g., one bit per band or one bit per band combination). Additionallyor alternatively, for intra-band switching, signaling may include onebit to indicate a long or a short gap for switching within the band. Insome examples, an additional bit, which may be called a “learningcapability bit,” may further be used. For instance, if a UE 115 iscapable, a long gap may be utilized for a certain band or within a band,after which a short gap may then be used for switching. The UE 115 mayindicate this capability to base station 105 using the “learningcapability bit.”

Wireless communications system 200 may also support PRACH transmissionon auxiliary UL CCs 215 (e.g., in order to obtain UL timing forauxiliary UL CCs 215). Instead of contention based PRACH, non-contentionbased PRACH may be supported and may be triggered via downlink controlinformation from a PCell or a PSCell. For example, wirelesscommunications system 200 may support PRACH on auxiliary UL CCs 215,particularly when the UE 115 is configured with two or more timingadvance groups (TAGs). Auxiliary UL CCs 215 and UL CCs 210 of a CAconfiguration may be associated with different TAGs, in which case,different UL timing for auxiliary UL CCs 215 may be used. In such cases,different UL timing may allow A-SRS transmissions to be orthogonal to ULtransmissions from other UEs 115 on the same CC.

In other examples, such as those employing dual-connectivity, switchingfor A-SRS transmissions may apply to each group of carriers configuredfor dual-connectivity. The configuration of one or more auxiliary UL CCs215 may be separately configured for each group. For example, a PCG mayhave no auxiliary UL CC 215 configured, while an SCG may be configuredwith one auxiliary UL CC 215. A similar scheme may be employed in CA iftwo PUCCH groups are configured.

In one example, the transmission of A-SRS in auxiliary UL CC 215 may betriggered based on a DL grant received on DL CC 205. Depending on thetransmission mode, the DL grant may be transmitted on the DL CC 205according to a number of different DCI formats. In some examples, eachDL grant for each transmission mode may include one or more bits totrigger the transmission of an A-SRS signal in auxiliary UL CC 215. Forexample, one bit in each of the DCI formats may indicate whether the DLgrant refers to a DL CC that shares its frequency resources with an ULCC (e.g., the DL CC and the UL CC are paired CCs), or whether the DLrefers to a DL CC that does not share its frequency resources with an ULCC (e.g., the DL CC and the UL CC are unpaired CCs). The bit may be apart of an A-SRS request field (e.g., SRS or A-SRS trigger field). Insome examples, a new bit or bits may be added to each of the DCI formatsto convey the indication. In other examples, an existing bit may berepurposed for such indication. In some examples, a combination of bitsmay be added and repurposed for the various DCI formats. A UE 115 thatreceives a DL grant in the DCI format may then determine whether anA-SRS should be transmitted to the requesting base station 105, forexample in auxiliary UL CC 215.

According to other examples, resources of auxiliary UL CC 215 may beselected (from among a set of available resources available fortransmission of A-SRSs) for transmission of an A-SRS based at least inpart on the DCI format associated with the DL grant. For example, if afirst DL grant is received in a first DCI format (e.g., DCI format 1A)at a first time, first resources (e.g., one or more resource blocks) ofauxiliary UL CC 215 may be used to send the A-SRS; if a second DL grantis later received in a different DCI format (e.g., DCI format 2B),different resources (e.g., a different one or more resource blocks) ofauxiliary UL CC 215 may be selected to transmit an A-SRS.

When a UE 115 has received the A-SRS trigger (e.g., by receiving a bitindicating such trigger in an A-SRS trigger field of a DL grant), UE 115may provide power control for the A-SRS transmitted on the auxiliary ULCC 215.

In some examples, the transmitter power control (TPC) command field fora DCI format may be conditional, such that UE 115 uses the power controlinformation in the TPC command field for power control of a PUCCH whenthe A-SRS trigger field does not indicate for UE 115 to transmit A-SRS,and UE 115 uses the power control information in the TPC command fieldfor power control of a A-SRS when the A-SRS trigger field indicates forUE 115 to transmit an A-SRS.

In other examples, power control information may be provided to UE 115for power control of an A-SRS in a field of the DCI format dedicated toan A-SRS TPC command. Thus, when an A-SRS trigger is indicated in a DLgrant according to the above modified DCI formats, then a A-SRS TPCcommand field may be present. In some examples, the A-SRS TPC commandfield may be always present, although not used for a A-SRS TPC commandunless the A-SRS trigger is indicated.

In further examples, UE 115 may continuously monitor for DCI in a DCIformat associated with UL power control (e.g., legacy LTE DCI formats 3and 3A) when UE 115 is configured according to an auxiliary ULconfiguration (e.g., to aperiodically transmit an A-SRS in auxiliary ULCC 215). UL power control information for an A-SRS may then bedetermined from DCI received in DCI format 3 and 3A.

In a second example, the transmission of A-SRS in auxiliary UL CC 215may be triggered based on an UL grant received on DL CC 205. In someexamples the UL grant may be a legacy UL grant (e.g., having DCI format0) that is interpreted to trigger an A-SRS when certain fields orparameters are set to predetermined values. The UL grant may beconfigured by base station 105 such that an A-SRS may be triggered whenUE 115 interprets a certain field or fields of the UL grant as includinga predetermined combination of values. Base station 105 may includecertain values or contents in the UL grant that would otherwise be usedfor transmitting PUSCH (e.g., MCS, number of resource blocks, etc.) totrigger an A-SRS. In other words, an A-SRS may be transmitted instead oftransmitting PUSCH data. For example, one bit in the DCI formatassociated with the UL grant may indicate whether the UL grant refers toa DL CC that shares its frequency resources with an UL CC (e.g., the DLCC 205 and the CA UL CC 210 are paired CCs), or whether the UL grantrefers to a DL CC that does not share its frequency resources with an ULCC (e.g., the DL CC 205 and the CA UL CC 210 are unpaired CCs). If UE115 determines that the DCI format associated with the UL grantindicates it is associated with the latter (e.g., unpaired CCs), then UE115 may evaluate certain contents of the UL grant to determine whetherthe contents has to be set to certain predetermined values to triggerthe transmission of an A-SRS by UE 115 to base station 105. For example,UE 115 may be preconfigured to trigger the transmission of an A-SRS ifMCS in an UL grant is set to 29 and the number of resource blocks isalso set to a certain value. Such resources may be available, forexample, because UE 115 may be configured to monitor for UL grants forA-SRS transmission.

In other examples, an UL grant that refers to a DL CC that shares itsfrequency resources with an UL CC (e.g., the DL CC 205 and the CA UL CC210 are paired CCs), may be used to trigger an A-SRS. In some examples,bits in an UL grant may be used to trigger A-SRSs associated with anumber of different auxiliary UL CCs 215 in a particular auxiliary ULconfiguration. For example, UE 115 may have an auxiliary ULconfiguration (e.g., an A-SRS configuration) that uses two or more DLCCs that do not have UL CCs associated with the same frequency resources(e.g., there are two or more auxiliary UL CCs 215). Two or more bits inan UL grant that is transmitted in a DL CC 205 (e.g. that is paired witha CA UL CC 210) may then be used by base station 105 to trigger thetransmission of an A-SRS in each of the auxiliary UL CCs 215. In anexample, two bits in the DL grant may be used to trigger zero, one, orboth of a first A-SRS and a second A-SRS in a first auxiliary UL CC 215and a second auxiliary UL CC 215, respectively. In some examples, thefirst A-SRS is time domain multiplexed with the second A-SRS.

In a third example, the transmission of an A-SRS in auxiliary UL CC 215may be triggered as part of a group trigger that is dedicated per UE. ADCI format may be defined for a grant that may be used to trigger one ormore A-SRS transmissions for a number of auxiliary UL CCs 215. Forexample, UE 115 may be configured to transmit an A-SRS in one or more of31 auxiliary UL CCs 215. The DCI format may include 5 bits to specifywhich of the 31 auxiliary UL CCs should be used to transmit an A-SRSassociated with a corresponding DL CC 205. In other examples, multipleA-SRSs may be triggered at the same time using more than 5 bits (e.g.,31 bits in the DCI format may allow each possible combination of A-SRSto be triggered for the 31 auxiliary UL CCs 215 corresponding to 31 DLCCs 205).

In some cases, additional parameters may be added to the DCI format, forexample, to specify an order or other pattern for transmission of theA-SRSs in a time domain multiplexed manner. An additional parameter mayprovide power control information for one or more of the auxiliary ULCCs 215. In some cases, an additional parameter in the DCI format mayprovide timing advance (TA) information for multiple carriers, or for atiming advance group (TAG), or an A-SRS resource to use to transmit theA-SRS. In some examples, one or more of a combination of the additionalparameters may be specified by fields included in the DCI format. Insome examples, the DCI format may have the same length as one or morelegacy DCI formats so that blind decoding by UE 115 may be simpler.

In a fourth example, the transmission of an A-SRS in auxiliary UL CC 215may be triggered for a group of UEs (e.g., both UE 115-a and UE 115-b)by the same grant from base station 105-a. A DCI format (e.g., a groupDCI) may be defined for the grant that may be used to trigger A-SRS forthe multiple UEs, where each UE may also be triggered to transmit one ormore A-SRSs on one or more of auxiliary UL CCs 215. For example, 4 bitsin the grant associated with the DCI format may be used to trigger twodifferent A-SRS in each of two different UEs. For example, the first twobits of the grant may be associated with UE 115-a, and may be used totrigger two A-SRSs on two auxiliary UL CCs 215 (each auxiliary UL CCcorresponding to a DL CC 205 sharing the same frequency resources), andthe second two bits of the grant may be associated with UE 115-b, andmay be used to trigger two A-SRSs on two auxiliary UL CCs 215. In someexamples, the group DCI may be transmitted by a PCC. In other examples,the group DCI may be transmitted by the PSCell. In some cases, anoverhead associated with a group DCI may be reduced as compared toindividual UE grants.

In some implementations, a scheduler of base station 105-a may resolvecollisions between A-SRS and other uplink transmissions that may not betransmitted together. In some situations periodic SRS and A-SRStransmissions may collide. The scheduler of base station 105-a maydetermine whether to transmit the SRS, A-SRS, the other uplinktransmissions, or all of them based on a preconfigured hierarchy ofsignaling. In one example, base station 105-a may use the preconfiguredhierarchy of signaling to resolve collisions. In one example a HARQPUCCH may be assigned a highest priority, followed by a PUCCH containingCSI feedback with a next lowest priority, followed by a dynamicallyscheduled PUSCH with a next lowest priority, followed by an A-SRS with anext lowest priority, followed by a SPS PUSCH with a next lowestpriority, followed by periodic SRS with a lowest priority. In otherimplementations, base station 105-a may be configured to resolvecollisions according to a different prioritization hierarchy, orincluding more or fewer types of UL and/or DL transmissions.

FIG. 3 illustrates an example of a CC configuration 300 that supportsA-SRS triggering for eCA. In some cases, CC configuration 300 mayrepresent aspects of techniques performed by a UE 115 or base station105 as described with reference to FIGS. 1-2. FIG. 3 illustrates CCs inthree CC configurations, including a CA configuration, an auxiliary ULconfiguration, and UL CCs that are unconfigured. Some of the DL CCs 305share frequency resources with one of UL CCs 310. In particular, a DL CCand UL CC that share the same frequency resources 315 (e.g., the UL CCand DL CC may be considered to be paired, or a pair of CCs), and a DL CCand UL CC that share the same frequency resources 320 (e.g., the UL CCand DL CC may be considered to be paired or a pair of CCs), are eachpart of the CA configuration. The CA configuration also includes DL CCs305, associated with frequency resources 325 and 330, that do not sharefrequency resources 325 and 330 with an UL CC in the CA configuration(e.g., the DL CC is not paired with a corresponding UL CC, or the CCsare unpaired CCs in the CA configuration). An UL CC 310 may beassociated with frequency resources 325 and be part of an auxiliary ULconfiguration that may be used, e.g., to transmit an A-SRS. An UL CC 310may be associated with frequency resources 330 and not be part of aconfiguration at a given time, such that only a DL CC 305 is associatedwith frequency resources 330.

FIG. 4 illustrates an example of a process flow 400 for A-SRS triggeringfor eCA. In some cases, process flow 400 may represent aspects oftechniques performed by a UE 115 or base station 105 as described withreference to FIGS. 1-2.

At 405, base station 105-b may transmit, and UE 115-c may receive, CAconfiguration information, including a CA configuration and an auxiliaryUL configuration for UE 115-c. The CA configuration may include one ormore UL CCs and one or more DL CCs for UE 115-c to use to transmit andreceive data with base station 105-b. The auxiliary UL configuration(e.g., an A-SRS configuration) may include one or more auxiliary UL CCs,outside the CA configuration used for data transmissions, that UE 115-cmay use to transmit A-SRSs to base station 105-b, for example whentriggered to do so by base station 105-b.

At 410, base station 105-b may transmit, and UE 115-c may receive, a DLtransmission on one or more DL CCs, including a resource assignment. Theresource assignment may be one or more of a DL grant, an UL grant,including a repurposed UL grant, a group grant, or other resourceassignments as described above with reference to FIGS. 1-2.

At 420, UE 115-c may transmit an A-SRS as an UL transmission on anauxiliary UL CC based on the received resource assignment. An A-SRS maybe triggered as further described above with reference to FIGS. 1-2.

UE 115-c may also transmit UL transmissions to base station 105-b usingone or more CA UL CCs (e.g., which may be paired with one or more DL CCsused for DL transmissions) at 415, either at the same or different timesas the A-SRS.

FIG. 5 illustrates an example of a process flow 500 for A-SRS triggeringfor eCA. In some cases, process flow 500 may represent aspects oftechniques performed by a UE 115 or base station 105 as described withreference to FIGS. 1-2.

At 505, base station 105-c may transmit, and UE 115-d may receive, A-SRSconfiguration information, including a CA configuration and an A-SRSconfiguration (e.g., an auxiliary UL configuration) for UE 115-c. Insome examples, a radio resource control (RRC) message including theA-SRS configuration information may be sent at 505. The CA configurationmay include one or more UL CCs and one or more DL CCs for UE 115-d touse to transmit and receive data with base station 105-c. The A-SRSconfiguration may include one or more UL CCs for A-SRS transmissions,outside the CA configuration used for data transmissions, that UE 115-dmay use to transmit A-SRSs to base station 105-c, for example whentriggered to do so by base station 105-b.

At 510, base station 105-c may transmit, and UE 115-d may receive, a DLtransmission on one or more DL CCs, including a resource assignment. Theresource assignment may be one or more of a DL grant, an UL grant,including a repurposed UL grant, a group grant, or other resourceassignments as described above with reference to FIGS. 1-2.

At 515, UE 115-d may detect a trigger for transmitting an A-SRS based onthe resource assignment received from base station 105-c. An A-SRS maybe triggered as further described above with reference to FIGS. 1-2.

At 520, UE 115-d may determine UL resources of the A-SRS configurationto use to transmit the A-SRS, or one or more A-SRSs, to base station105-c. UL resources may be determined as further described above withreference to FIGS. 1-2.

At 530, UE 115-c may transmit one or more A-SRSs as an UL transmissionon an UL CC based on the determined resource assignment. In someexamples, the UL CCs used to transmit the one or more A-SRSs may sharefrequency resources with one or more dedicated DL CCs used for datatransmission from base station 105-c to UE 115-d according to the CAconfiguration.

UE 115-d may also transmit UL transmissions to base station 105-c usingone or more CA UL CCs (e.g., which may be paired with one or more DL CCsused for DL transmissions) at 525, either at the same or different timesas the A-SRS.

FIG. 6 shows a block diagram of a wireless device 600 that supportsA-SRS triggering for eCA in accordance with various aspects of thepresent disclosure. Wireless device 600 may be an example of aspects ofa UE 115 described with reference to FIGS. 1 and 2. Wireless device 600may include receiver 605, UE auxiliary uplink manager 610 andtransmitter 615. Wireless device 600 may also include a processor. Eachof these components may be in communication with each other.

The receiver 605 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to A-SRStriggering for eCA, etc.). Information may be passed on to othercomponents of the device. The receiver 605 may be an example of aspectsof the transceiver 925 described with reference to FIG. 9.

The UE auxiliary uplink manager 610 may identify a CA configuration andan A-SRS configuration, receive a resource assignment on a DL carrier inthe CA configuration, detect a trigger for transmitting an A-SRS basedon the resource assignment, determine UL resources of the A-SRSconfiguration for transmitting the A-SRS, transmit the A-SRS on thedetermined UL resources, receive signaling that indicates a CAconfiguration and an auxiliary UL configuration, the CA configurationcomprising one or more carriers configured for UL and DL datatransmissions, and the auxiliary UL configuration comprising one or morecarriers configured for UL reference signal transmissions, receive aresource assignment on a DL carrier of the CA configuration, andtransmit an A-SRS using the one or more carriers of the auxiliary ULconfiguration based on the received resource assignment. The UEauxiliary uplink manager 610 may also be an example of aspects of the UEauxiliary uplink manager 905 described with reference to FIG. 9.

The transmitter 615 may transmit signals received from other componentsof wireless device 600. In some examples, the transmitter 615 may becollocated with a receiver in a transceiver module. For example, thetransmitter 615 may be an example of aspects of the transceiver 925described with reference to FIG. 9. The transmitter 615 may include asingle antenna, or it may include a plurality of antennas.

FIG. 7 shows a block diagram of a wireless device 700 that supportsA-SRS triggering for eCA in accordance with various aspects of thepresent disclosure. Wireless device 700 may be an example of aspects ofa wireless device 600 or a UE 115 described with reference to FIGS. 1, 2and 6. Wireless device 700 may include receiver 705, UE auxiliary uplinkmanager 710 and transmitter 735. Wireless device 700 may also include aprocessor. Each of these components may be in communication with eachother.

The receiver 705 may receive information which may be passed on to othercomponents of the device. The receiver 705 may also perform thefunctions described with reference to the receiver 605 of FIG. 6. Thereceiver 705 may be an example of aspects of the transceiver 925described with reference to FIG. 9.

The UE auxiliary uplink manager 710 may be an example of aspects of UEauxiliary uplink manager 610 described with reference to FIG. 6. The UEauxiliary uplink manager 710 may include configuration component 715,resource assignment component 720, A-SRS component 725 and A-SRS triggercomponent 730. The UE auxiliary uplink manager 710 may be an example ofaspects of the UE auxiliary uplink manager 905 described with referenceto FIG. 9.

The configuration component 715 may receive an RRC message to configurethe UE with the CA configuration and the auxiliary UL configuration,where the RRC message includes A-SRS configurations for a set of UEs,receive an A-SRS configuration, where the A-SRS configuration identifiesone or more UL carriers dedicated for transmitting the A-SRS, receive anRRC message to configure the UE with the CA configuration and the A-SRSconfiguration, where the RRC message includes A-SRS configurations for aset of UEs, and receive signaling that indicates a CA configuration andan auxiliary UL configuration, the CA configuration comprising one ormore carriers configured for UL and DL data transmissions, and theauxiliary UL configuration comprising one or more carriers configuredfor UL reference signal transmissions. In some cases, the auxiliary ULconfiguration comprises an A-SRS configuration. In some cases, a DLcarrier of the CA configuration and a carrier of the auxiliary ULconfiguration share frequency resources.

The resource assignment component 720 may identify resource for UL or DLtransmissions, determine that the received resource assignment isassociated with the auxiliary UL configuration and is in the resourceassignment format, determine a resource assignment format associatedwith the received resource assignment, determine resources used totransmit the A-SRS based on the determined resource assignment format,identify the resource assignment as for an UL data transmission,determine to transmit the A-SRS based on the identification, receive, inthe resource assignment, an UL grant associated with a set of A-SRSs fora set of carriers based on the received resource assignment, identifyresources for the A-SRS to be transmitted using the one or more carriersof the auxiliary UL configuration, receive a resource assignment on a DLcarrier in the CA configuration, determine UL resources of the A-SRSconfiguration for transmitting the A-SRS, and receive a resourceassignment on a DL carrier of the CA configuration.

In some cases, the resource assignment comprises a DL grant. In somecases, the resource assignment comprises an UL grant for resources ofthe one or more carriers configured for UL data transmissions. In somecases, the resource assignment comprises a DL grant having a formatselected from a set of available DL grant formats based on atransmission mode of the UE, where each DL grant formats of the set ofavailable DL grant formats comprise an A-SRS trigger when the UE isconfigured with the A-SRS configuration. In some cases, the resourceassignment comprises a sounding reference signal radio network temporaryidentifier (SRS-RNTI), where the SRS-RNTI triggers a set of A-SRSs in aset of UL resources of the A-SRS configuration.

The A-SRS component 725 may transmit the A-SRS transmissions on thedetermined UL CCs, and transmit an A-SRS using the one or more carriersof the auxiliary UL configuration based on the received resourceassignment. The A-SRS trigger component 730 may detect a trigger fortransmitting A-SRS transmissions using UL CCs based on a DCI format ofthe resource assignment.

The transmitter 735 may transmit signals received from other componentsof wireless device 700. In some examples, the transmitter 735 may becollocated with a receiver in a transceiver module. For example, thetransmitter 735 may be an example of aspects of the transceiver 925described with reference to FIG. 9. The transmitter 735 may utilize asingle antenna, or it may utilize a plurality of antennas.

FIG. 8 shows a block diagram of a UE auxiliary uplink manager 800 whichmay be an example of the corresponding component of wireless device 600or wireless device 700. That is, UE auxiliary uplink manager 800 may bean example of aspects of UE auxiliary uplink manager 610 or UE auxiliaryuplink manager 710 described with reference to FIGS. 6 and 7. The UEauxiliary uplink manager 800 may also be an example of aspects of the UEauxiliary uplink manager 905 described with reference to FIG. 9.

The UE auxiliary uplink manager 800 may include configuration component805, A-SRS component 810, monitoring component 815, carrieridentification component 820, resource assignment component 825,simultaneous transmission component 830, A-SRS trigger component 835,A-SRS request component 840 and power control component 845. Each ofthese modules may communicate, directly or indirectly, with one another(e.g., via one or more buses).

The configuration component 805 may receive an RRC message to configurethe UE with the CA configuration and the auxiliary UL configuration,where the RRC message includes A-SRS configurations for a set of UEs,receive an A-SRS configuration, where the A-SRS configuration identifiesone or more UL carriers dedicated for transmitting the A-SRS, receive anRRC message to configure the UE with the CA configuration and the A-SRSconfiguration, where the RRC message includes A-SRS configurations for aset of UEs, and receive signaling that indicates a CA configuration andan auxiliary UL configuration, the CA configuration comprising one ormore carriers configured for UL and DL data transmissions, and theauxiliary UL configuration comprising one or more carriers configuredfor UL reference signal transmissions.

The A-SRS component 810 may transmit the A-SRS transmissions on thedetermined UL CCs, and transmit an A-SRS using the one or more carriersof the auxiliary UL configuration based on the received resourceassignment. The monitoring component 815 may monitor the DL carrier ofthe CA configuration for a resource assignment format associated with anUL power control.

The carrier identification component 820 may identify a set of carriersof the auxiliary UL configuration based on the received resourceassignment, identify auxiliary based on a plurality of bits of theresource assignment configured according to a DCI format, transmit a setof A-SRSs on the identified set of carriers, and identify, for the UE,the one or more carriers of the auxiliary UL configuration to be used totransmit the A-SRS of the set of A-SRSs associated with the UE. In somecases, the resource assignment comprises a set of A-SRS trigger bits toindicate the set of carriers. In some cases, the resource assignmentcomprises an indication of a time domain multiplexed (TDM) ordering ofthe set of A-SRSs, power control information for the set of carriers, ortiming advance information for the set of carriers.

The resource assignment component 825 may determine that the receivedresource assignment is associated with the auxiliary UL configurationand is in the resource assignment format, determine a resourceassignment format associated with the received resource assignment,determine resources used to transmit the A-SRS based on the determinedresource assignment format, identify the resource assignment as for anUL data transmission, determine to transmit the A-SRS based on theidentification, receive, in the resource assignment, an UL grantassociated with a set of A-SRSs for a set of carriers based on thereceived resource assignment, identify resources for the A-SRS to betransmitted using the one or more carriers of the auxiliary ULconfiguration, receive a resource assignment on a DL carrier in the CAconfiguration, determine UL CCs of the A-SRS configuration fortransmitting the A-SRS transmissions based on the DCI format of theresource assignment, and receive a resource assignment on a DL carrierof the CA configuration.

The simultaneous transmission component 830 may identify that an ULchannel is to be transmitted simultaneously on the one or more of theauxiliary UL configuration, identify non-A-SRS uplink transmissions tobe transmitted simultaneously with A-SRS transmissions, and determinewhether to transmit the A-SRS transmissions, the non-A-SRStransmissions, or both according to a priority hierarchy.

The A-SRS trigger component 835 may detect a detect a trigger fortransmitting A-SRS transmissions using UL CCs based on a DCI format ofthe resource assignment. The A-SRS request component 840 may receive anA-SRS request field in the resource assignment, and determine totransmit the A-SRS based on the A-SRS request field.

The power control component 845 may receive, in the resource assignment,a power control command, identify power control information in a fieldof a DCI format that includes an A-SRS TPC command, determine a transmitpower based at least on the power control command, transmit the A-SRSbased on the transmit power, and identify one or more bits of theresource assignment format as associated with power control for theA-SRS. In some cases, the power control command is transmitted usingsignaling that is for an UL control channel absent the power controlcommand associated with the A-SRS. In some cases, the power controlcommand comprises an explicit indication of power control for the A-SRSin the resource assignment.

FIG. 9 shows a diagram of a system 900 including a device that supportsA-SRS triggering for eCA in accordance with various aspects of thepresent disclosure. For example, system 900 may include UE 115-e, whichmay be an example of a wireless device 600, a wireless device 700, or aUE 115 as described with reference to FIGS. 1, 2 and 6 through 8.

UE 115-e may also include UE auxiliary uplink manager 905, memory 910,processor 920, transceiver 925, antenna 930 and ECC module 935. Each ofthese modules may communicate, directly or indirectly, with one another(e.g., via one or more buses). The UE auxiliary uplink manager 905 maybe an example of a UE auxiliary uplink manager as described withreference to FIGS. 6 through 8.

The memory 910 may include random access memory (RAM) and read onlymemory (ROM). The memory 910 may store computer-readable,computer-executable software including instructions that, when executed,cause the processor to perform various functions described herein (e.g.,A-SRS triggering for eCA, etc.). In some cases, the software 915 may notbe directly executable by the processor but may cause a computer (e.g.,when compiled and executed) to perform functions described herein. Theprocessor 920 may include an intelligent hardware device, (e.g., acentral processing unit (CPU), a microcontroller, an applicationspecific integrated circuit (ASIC), etc.)

The transceiver 925 may communicate bi-directionally, via one or moreantennas, wired, or wireless links, with one or more networks, asdescribed above. For example, the transceiver 925 may communicatebi-directionally with a base station 105 or a UE 115. The transceiver925 may also include a modem to modulate the packets and provide themodulated packets to the antennas for transmission, and to demodulatepackets received from the antennas. In some cases, the wireless devicemay include a single antenna 930. However, in some cases the device mayhave more than one antenna 930, which may be capable of concurrentlytransmitting or receiving multiple wireless transmissions.

ECC module 935 may enable operations using ECCs such as communicationusing shared or unlicensed spectrum, using reduced TTIs or subframedurations, or using a large number of component carriers.

FIG. 10 shows a block diagram of a wireless device 1000 that supportsA-SRS triggering for eCA in accordance with various aspects of thepresent disclosure. Wireless device 1000 may be an example of aspects ofa base station 105 described with reference to FIGS. 1 and 2. Wirelessdevice 1000 may include receiver 1005, base station auxiliary uplinkmanager 1010 and transmitter 1015. Wireless device 1000 may also includea processor. Each of these components may be in communication with eachother.

The receiver 1005 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to A-SRStriggering for eCA, etc.). Information may be passed on to othercomponents of the device. The receiver 1005 may be an example of aspectsof the transceiver 1325 described with reference to FIG. 13.

The base station auxiliary uplink manager 1010 may transmit signalingthat indicates a CA configuration and an auxiliary UL configuration fora UE, the CA configuration comprising one or more carriers configuredfor UL and DL data transmissions, and the auxiliary UL configurationcomprising one or more carriers configured for UL reference signaltransmissions, transmit a resource assignment on a DL carrier of the oneor more carriers of the CA configuration, and receive an A-SRS using theone or more carriers of the auxiliary UL configuration in response tothe transmitted resource assignment. The base station auxiliary uplinkmanager 1010 may also be an example of aspects of the base stationauxiliary uplink manager 1305 described with reference to FIG. 13.

The transmitter 1015 may transmit signals received from other componentsof wireless device 1000. In some examples, the transmitter 1015 may becollocated with a receiver in a transceiver module. For example, thetransmitter 1015 may be an example of aspects of the transceiver 1325described with reference to FIG. 13. The transmitter 1015 may include asingle antenna, or it may include a plurality of antennas.

FIG. 11 shows a block diagram of a wireless device 1100 that supportsA-SRS triggering for eCA in accordance with various aspects of thepresent disclosure. Wireless device 1100 may be an example of aspects ofa wireless device 1000 or a base station 105 described with reference toFIGS. 1, 2 and 10. Wireless device 1100 may include receiver 1105, basestation auxiliary uplink manager 1110 and transmitter 1130. Wirelessdevice 1100 may also include a processor. Each of these components maybe in communication with each other.

The receiver 1105 may receive information which may be passed on toother components of the device. The receiver 1105 may also perform thefunctions described with reference to the receiver 1005 of FIG. 10. Thereceiver 1105 may be an example of aspects of the transceiver 1325described with reference to FIG. 13.

The base station auxiliary uplink manager 1110 may be an example ofaspects of base station auxiliary uplink manager 1010 described withreference to FIG. 10. The base station auxiliary uplink manager 1110 mayinclude resource assignment component 1115, A-SRS component 1120 andconfiguration component 1125. The base station auxiliary uplink manager1110 may be an example of aspects of the base station auxiliary uplinkmanager 1305 described with reference to FIG. 13.

The resource assignment component 1115 may transmit a resourceassignment on a DL carrier of the one or more carriers of the CAconfiguration, transmit, in the resource assignment, a power controlcommand, where the A-SRS is based on the power control command, andtransmit the resource assignment according to a resource assignmentformat, where the A-SRS is based on the resource assignment format.

In some cases, the resource assignment comprises a DL grant. In somecases, the transmitted resource assignment comprises a resourceassignment format associated with an UL power control and including oneor more bits associated with power control for the A-SRS. In some cases,the resource assignment comprises a resource assignment for an UL datatransmission and the A-SRS is based on an identification of the resourceassignment as for the UL data transmission.

The A-SRS component 1120 may receive A-SRS transmissions on determinedUL carriers, and receive, from the set of UEs and based on the UL grant,a set of A-SRSs using the one or more carriers of the auxiliary ULconfiguration.

The configuration component 1125 may transmit signaling that indicates aCA configuration and an auxiliary UL configuration for a UE, the CAconfiguration comprising one or more carriers configured for UL and DLdata transmissions, and the auxiliary UL configuration comprising one ormore carriers configured for UL reference signal transmissions, andtransmit an RRC message to configure a set of UEs with a set of CA andauxiliary UL configurations, including the UE with the CA configurationand the auxiliary UL configuration.

The transmitter 1130 may transmit signals received from other componentsof wireless device 1100. In some examples, the transmitter 1130 may becollocated with a receiver in a transceiver module. For example, thetransmitter 1130 may be an example of aspects of the transceiver 1325described with reference to FIG. 13. The transmitter 1130 may utilize asingle antenna, or it may utilize a plurality of antennas.

FIG. 12 shows a block diagram of a base station auxiliary uplink manager1200 which may be an example of the corresponding component of wirelessdevice 1000 or wireless device 1100. That is, base station auxiliaryuplink manager 1200 may be an example of aspects of base stationauxiliary uplink manager 1010 or base station auxiliary uplink manager1110 described with reference to FIGS. 10 and 11. The base stationauxiliary uplink manager 1200 may also be an example of aspects of thebase station auxiliary uplink manager 1305 described with reference toFIG. 13.

The base station auxiliary uplink manager 1200 may include resourceassignment component 1205, A-SRS component 1210, A-SRS request component1215, configuration component 1220 and UL grant component 1225. Each ofthese modules may communicate, directly or indirectly, with one another(e.g., via one or more buses).

The resource assignment component 1205 may transmit a resourceassignment on a DL carrier of the one or more carriers of the CAconfiguration, transmit power control information in a field of a DCIformat that indicated an A-SRS TPC command, transmit, in the resourceassignment, a power control command, where the A-SRS is based on thepower control command, and transmit the resource assignment according toa resource assignment format, where the A-SRS is based on the resourceassignment format.

The A-SRS component 1210 may receive an A-SRS using the one or morecarriers of the auxiliary UL configuration in response to thetransmitted resource assignment, and receive, from the set of UEs andbased on the UL grant, a set of A-SRSs using the one or more carriers ofthe auxiliary UL configuration. The A-SRS request component 1215 maytransmit an A-SRS request field in the resource assignment, where theA-SRS is based on the A-SRS request field.

The configuration component 1220 may transmit signaling that indicates aCA configuration and an auxiliary UL configuration for a UE, the CAconfiguration comprising one or more carriers configured for UL and DLdata transmissions, and the auxiliary UL configuration comprising one ormore carriers configured for UL reference signal transmissions, andtransmit an RRC message to configure a set of UEs with a set of CA andauxiliary UL configurations, including the UE with the CA configurationand the auxiliary UL configuration.

The UL grant component 1225 may transmit, in the resource assignment, anUL grant associated with a set of UEs. In some cases, the resourceassignment comprises an UL grant for resources of the one or morecarriers configured for UL data transmissions.

FIG. 13 shows a diagram of a wireless system 1300 including a deviceconfigured that supports A-SRS triggering for eCA in accordance withvarious aspects of the present disclosure. For example, wireless system1300 may include base station 105-e, which may be an example of awireless device 1000, a wireless device 1100, or a base station 105 asdescribed with reference to FIGS. 1, 2 and 10 through 12. Base station105-e may also include components for bi-directional voice and datacommunications including components for transmitting communications andcomponents for receiving communications. For example, base station 105-emay communicate bi-directionally with one or more UEs 115.

Base station 105-e may also include base station auxiliary uplinkmanager 1305, memory 1310, processor 1320, transceiver 1325, antenna1330, base station communications module 1335 and network communicationsmodule 1340. Each of these modules may communicate, directly orindirectly, with one another (e.g., via one or more buses). The basestation auxiliary uplink manager 1305 may be an example of a basestation auxiliary uplink manager as described with reference to FIGS. 10through 12.

The memory 1310 may include RAM and ROM. The memory 1310 may storecomputer-readable, computer-executable software including instructionsthat, when executed, cause the processor to perform various functionsdescribed herein (e.g., A-SRS triggering for eCA, etc.). In some cases,the software 1315 may not be directly executable by the processor butmay cause a computer (e.g., when compiled and executed) to performfunctions described herein. The processor 1320 may include anintelligent hardware device, (e.g., a CPU, a microcontroller, an ASIC,etc.)

The transceiver 1325 may communicate bi-directionally, via one or moreantennas, wired, or wireless links, with one or more networks, asdescribed above. For example, the transceiver 1325 may communicatebi-directionally with a base station 105 or a UE 115. The transceiver1325 may also include a modem to modulate the packets and provide themodulated packets to the antennas for transmission, and to demodulatepackets received from the antennas. In some cases, the wireless devicemay include a single antenna 1330. However, in some cases the device mayhave more than one antenna 930, which may be capable of concurrentlytransmitting or receiving multiple wireless transmissions.

The base station communications module 1335 may manage communicationswith other base station 105, and may include a controller or schedulerfor controlling communications with UEs 115 in cooperation with otherbase stations 105. For example, the base station communications module1335 may coordinate scheduling for transmissions to UEs 115 for variousinterference mitigation techniques such as beamforming or jointtransmission. In some examples, base station communications module-95may provide an X2 interface within an LTE/LTE-A wireless communicationnetwork technology to provide communication between base stations 105.

The network communications module 1340 may manage communications withthe core network (e.g., via one or more wired backhaul links). Forexample, the network communications module 1340 may manage the transferof data communications for client devices, such as one or more UEs 115.

FIG. 14 shows a flowchart illustrating a method 1400 for A-SRStriggering for eCA in accordance with various aspects of the presentdisclosure. The operations of method 1400 may be implemented by a devicesuch as a UE 115 or its components as described with reference to FIGS.1 and 2. For example, the operations of method 1400 may be performed bythe UE auxiliary uplink manager as described herein. In some examples,the UE 115 may execute a set of codes to control the functional elementsof the device to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects the functions describedbelow using special-purpose hardware.

At block 1405, the UE 115 may receive signaling that indicates a CAconfiguration and an auxiliary UL configuration, the CA configurationcomprising one or more carriers configured for UL and DL datatransmissions, and the auxiliary UL configuration comprising one or morecarriers configured for UL reference signal transmissions as describedabove with reference to FIGS. 2 through 5. In certain examples, theoperations of block 1405 may be performed by the configuration componentas described with reference to FIGS. 7 and 8.

At block 1410, the UE 115 may receive a resource assignment on a DLcarrier of the CA configuration as described above with reference toFIGS. 2 through 5. In certain examples, the operations of block 1410 maybe performed by the resource assignment component as described withreference to FIGS. 7 and 8.

At block 1415, the UE 115 may transmit an A-SRS using the one or morecarriers of the auxiliary UL configuration based on the receivedresource assignment as described above with reference to FIGS. 2 through5. In certain examples, the operations of block 1415 may be performed bythe A-SRS component as described with reference to FIGS. 7 and 8.

FIG. 15 shows a flowchart illustrating a method 1500 for A-SRStriggering for eCA in accordance with various aspects of the presentdisclosure. The operations of method 1500 may be implemented by a devicesuch as a UE 115 or its components as described with reference to FIGS.1 and 2. For example, the operations of method 1500 may be performed bythe UE auxiliary uplink manager as described herein. In some examples,the UE 115 may execute a set of codes to control the functional elementsof the device to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects the functions describedbelow using special-purpose hardware.

At block 1505, the UE 115 may receive signaling that indicates a CAconfiguration and an auxiliary UL configuration, the CA configurationcomprising one or more carriers configured for UL and DL datatransmissions, and the auxiliary UL configuration comprising one or morecarriers configured for UL reference signal transmissions as describedabove with reference to FIGS. 2 through 5. In certain examples, theoperations of block 1505 may be performed by the configuration componentas described with reference to FIGS. 7 and 8.

At block 1510, the UE 115 may receive a resource assignment on a DLcarrier of the CA configuration as described above with reference toFIGS. 2 through 5. In certain examples, the operations of block 1510 maybe performed by the resource assignment component as described withreference to FIGS. 7 and 8.

At block 1515, the UE 115 may receive an A-SRS request field in theresource assignment as described above with reference to FIGS. 2 through5. In certain examples, the operations of block 1515 may be performed bythe A-SRS request component as described with reference to FIGS. 7 and8.

At block 1520, the UE 115 may determine to transmit the A-SRS based onthe A-SRS request field as described above with reference to FIGS. 2through 5. In certain examples, the operations of block 1520 may beperformed by the A-SRS request component as described with reference toFIGS. 7 and 8.

At block 1525, the UE 115 may transmit an A-SRS using the one or morecarriers of the auxiliary UL configuration based on the receivedresource assignment as described above with reference to FIGS. 2 through5. In certain examples, the operations of block 1525 may be performed bythe A-SRS component as described with reference to FIGS. 7 and 8.

FIG. 16 shows a flowchart illustrating a method 1600 for A-SRStriggering for eCA in accordance with various aspects of the presentdisclosure. The operations of method 1600 may be implemented by a devicesuch as a UE 115 or its components as described with reference to FIGS.1 and 2. For example, the operations of method 1600 may be performed bythe UE auxiliary uplink manager as described herein. In some examples,the UE 115 may execute a set of codes to control the functional elementsof the device to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects the functions describedbelow using special-purpose hardware.

At block 1605, the UE 115 may receive signaling that indicates a CAconfiguration and an auxiliary UL configuration, the CA configurationcomprising one or more carriers configured for UL and DL datatransmissions, and the auxiliary UL configuration comprising one or morecarriers configured for UL reference signal transmissions as describedabove with reference to FIGS. 2 through 5. In certain examples, theoperations of block 1605 may be performed by the configuration componentas described with reference to FIGS. 7 and 8.

At block 1610, the UE 115 may receive a resource assignment on a DLcarrier of the CA configuration as described above with reference toFIGS. 2 through 5. In certain examples, the operations of block 1610 maybe performed by the resource assignment component as described withreference to FIGS. 7 and 8.

At block 1615, the UE 115 may receive, in the resource assignment, apower control command as described above with reference to FIGS. 2through 5. In certain examples, the operations of block 1615 may beperformed by the power control component as described with reference toFIGS. 7 and 8.

At block 1620, the UE 115 may determine a transmit power based at leaston the power control command as described above with reference to FIGS.2 through 5. In certain examples, the operations of block 1620 may beperformed by the power control component as described with reference toFIGS. 7 and 8.

At block 1625, the UE 115 may transmit an A-SRS using the one or morecarriers of the auxiliary UL configuration based on the receivedresource assignment as described above with reference to FIGS. 2 through5. In some cases, the UE 115 may transmit the A-SRS based on thetransmit power. In certain examples, the operations of block 1625 may beperformed by the A-SRS component as described with reference to FIGS. 7and 8.

FIG. 17 shows a flowchart illustrating a method 1700 for A-SRStriggering for eCA in accordance with various aspects of the presentdisclosure. The operations of method 1700 may be implemented by a devicesuch as a UE 115 or its components as described with reference to FIGS.1 and 2. For example, the operations of method 1700 may be performed bythe UE auxiliary uplink manager as described herein. In some examples,the UE 115 may execute a set of codes to control the functional elementsof the device to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects the functions describedbelow using special-purpose hardware.

At block 1705, the UE 115 may receive signaling that indicates a CAconfiguration and an auxiliary UL configuration, the CA configurationcomprising one or more carriers configured for UL and DL datatransmissions, and the auxiliary UL configuration comprising one or morecarriers configured for UL reference signal transmissions as describedabove with reference to FIGS. 2 through 5. In certain examples, theoperations of block 1705 may be performed by the configuration componentas described with reference to FIGS. 7 and 8.

At block 1710, the UE 115 may receive a resource assignment on a DLcarrier of the CA configuration as described above with reference toFIGS. 2 through 5. In certain examples, the operations of block 1710 maybe performed by the resource assignment component as described withreference to FIGS. 7 and 8.

At block 1715, the UE 115 may receive, in the resource assignment, an ULgrant associated with a set of A-SRSs for a set of carriers based on thereceived resource assignment as described above with reference to FIGS.2 through 5. In certain examples, the operations of block 1715 may beperformed by the resource assignment component as described withreference to FIGS. 7 and 8.

At block 1720, the UE 115 may identify, for the UE, the one or morecarriers of the auxiliary UL configuration to be used to transmit theA-SRS of the set of A-SRSs associated with the UE as described abovewith reference to FIGS. 2 through 5. In certain examples, the operationsof block 1720 may be performed by the carrier identification componentas described with reference to FIGS. 7 and 8.

At block 1725, the UE 115 may transmit an A-SRS using the one or morecarriers of the auxiliary UL configuration based on the receivedresource assignment as described above with reference to FIGS. 2 through5. In certain examples, the operations of block 1725 may be performed bythe A-SRS component as described with reference to FIGS. 7 and 8.

FIG. 18 shows a flowchart illustrating a method 1800 for A-SRStriggering for eCA in accordance with various aspects of the presentdisclosure. The operations of method 1800 may be implemented by a devicesuch as a UE 115 or its components as described with reference to FIGS.1 and 2. For example, the operations of method 1800 may be performed bythe UE auxiliary uplink manager as described herein. In some examples,the UE 115 may execute a set of codes to control the functional elementsof the device to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects the functions describedbelow using special-purpose hardware.

At block 1805, the UE 115 may receive signaling that indicates a CAconfiguration and an auxiliary UL configuration, the CA configurationcomprising one or more carriers configured for UL and DL datatransmissions, and the auxiliary UL configuration comprising one or morecarriers configured for UL reference signal transmissions as describedabove with reference to FIGS. 2 through 5. In certain examples, theoperations of block 1805 may be performed by the configuration componentas described with reference to FIGS. 7 and 8.

At block 1810, the UE 115 may receive a resource assignment on a DLcarrier of the CA configuration as described above with reference toFIGS. 2 through 5. In certain examples, the operations of block 1810 maybe performed by the resource assignment component as described withreference to FIGS. 7 and 8.

At block 1815, the UE 115 may receive an RRC message to configure the UEwith the CA configuration and the auxiliary UL configuration, where theRRC message includes A-SRS configurations for a set of UEs as describedabove with reference to FIGS. 2 through 5. In certain examples, theoperations of block 1815 may be performed by the configuration componentas described with reference to FIGS. 7 and 8.

At block 1820, the UE 115 may transmit an A-SRS using the one or morecarriers of the auxiliary UL configuration based on the receivedresource assignment as described above with reference to FIGS. 2 through5. In certain examples, the operations of block 1820 may be performed bythe A-SRS component as described with reference to FIGS. 7 and 8.

FIG. 19 shows a flowchart illustrating a method 1900 for A-SRStriggering for eCA in accordance with various aspects of the presentdisclosure. The operations of method 1900 may be implemented by a devicesuch as a base station 105 or its components as described with referenceto FIGS. 1 and 2. For example, the operations of method 1900 may beperformed by the base station auxiliary uplink manager as describedherein. In some examples, the base station 105 may execute a set ofcodes to control the functional elements of the device to perform thefunctions described below. Additionally or alternatively, the basestation 105 may perform aspects the functions described below usingspecial-purpose hardware.

At block 1905, the base station 105 may transmit signaling thatindicates a CA configuration and an auxiliary UL configuration for a UE,the CA configuration comprising one or more carriers configured for ULand DL data transmissions, and the auxiliary UL configuration comprisingone or more carriers configured for UL reference signal transmissions asdescribed above with reference to FIGS. 2 through 5. In certainexamples, the operations of block 1905 may be performed by theconfiguration component as described with reference to FIGS. 11 and 12.

At block 1910, the base station 105 may transmit a resource assignmenton a DL carrier of the one or more carriers of the CA configuration asdescribed above with reference to FIGS. 2 through 5. In certainexamples, the operations of block 1910 may be performed by the resourceassignment component as described with reference to FIGS. 11 and 12.

At block 1915, the base station 105 may receive an A-SRS using the oneor more carriers of the auxiliary UL configuration in response to thetransmitted resource assignment as described above with reference toFIGS. 2 through 5. In certain examples, the operations of block 1915 maybe performed by the A-SRS component as described with reference to FIGS.11 and 12.

FIG. 20 shows a flowchart illustrating a method 2000 for A-SRStriggering for eCA in accordance with various aspects of the presentdisclosure. The operations of method 2000 may be implemented by a devicesuch as a UE 115 or its components as described with reference to FIGS.1 and 2. For example, the operations of method 2000 may be performed bythe UE auxiliary uplink manager as described herein. In some examples,the UE 115 may execute a set of codes to control the functional elementsof the device to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects the functions describedbelow using special-purpose hardware.

At block 2005, the UE 115 may identify a CA configuration and an A-SRSconfiguration of the UE 115 as described above with reference to FIGS. 2through 5. The A-SRS configuration may comprise of one or more componentcarriers (CCs) on which the UE does not perform UL data transmissions.In certain examples, the operations of block 2005 may be performed bythe

At block 2010, the UE 115 may receive a resource assignment on a DL CCin the CA configuration as described above with reference to FIGS. 2through 5. In certain examples, the operations of block 2010 may beperformed by the resource assignment component as described withreference to FIGS. 7 and 8.

At block 2015, the UE 115 may detect a trigger for transmitting an A-SRSbased on a DCI format of the resource assignment as described above withreference to FIGS. 2 through 5. In certain examples, the operations ofblock 2015 may be performed by the A-SRS trigger component as describedwith reference to FIGS. 7 and 8.

At block 2020, the UE 115 may determine CCs of the A-SRS configurationfor transmitting A-SRS transmissions based on the DCI format of theresource assignment as described above with reference to FIGS. 2 through5. In certain examples, the operations of block 2020 may be performed bythe resource assignment component as described with reference to FIGS. 7and 8.

At block 2025, the UE 115 may transmit the A-SRS on the determined CCsas described above with reference to FIGS. 2 through 5. In certainexamples, the operations of block 2025 may be performed by the A-SRScomponent as described with reference to FIGS. 7 and 8.

FIG. 21 shows a flowchart illustrating a method 2100 for A-SRStriggering for eCA in accordance with various aspects of the presentdisclosure. The operations of method 2100 may be implemented by a devicesuch as a UE 115 or its components as described with reference to FIGS.1 and 2. For example, the operations of method 2100 may be performed bythe UE auxiliary uplink manager as described herein. In some examples,the UE 115 may execute a set of codes to control the functional elementsof the device to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects the functions describedbelow using special-purpose hardware.

At block 2105, the UE 115 may receive an A-SRS configuration, where theA-SRS configuration identifies one or more UL carriers dedicated fortransmitting the A-SRS as described above with reference to FIGS. 2through 5. In certain examples, the operations of block 2105 may beperformed by the configuration component as described with reference toFIGS. 7 and 8.

At block 2110, the UE 115 may receive a resource assignment on a DLcarrier in the CA configuration as described above with reference toFIGS. 2 through 5. In certain examples, the operations of block 2110 maybe performed by the resource assignment component as described withreference to FIGS. 7 and 8.

At block 2115, the UE 115 may detect a trigger for transmitting an A-SRSbased on the resource assignment as described above with reference toFIGS. 2 through 5. In certain examples, the operations of block 2115 maybe performed by the A-SRS trigger component as described with referenceto FIGS. 7 and 8.

At block 2120, the UE 115 may determine UL resources of the A-SRSconfiguration for transmitting the A-SRS as described above withreference to FIGS. 2 through 5. In certain examples, the operations ofblock 2120 may be performed by the resource assignment component asdescribed with reference to FIGS. 7 and 8.

At block 2125, the UE 115 may transmit the A-SRS on the determined ULresources as described above with reference to FIGS. 2 through 5. Incertain examples, the operations of block 2125 may be performed by theA-SRS component as described with reference to FIGS. 7 and 8.

FIG. 22 shows a flowchart illustrating a method 2200 for A-SRStriggering for eCA in accordance with various aspects of the presentdisclosure. The operations of method 2200 may be implemented by a devicesuch as a UE 115 or its components as described with reference to FIGS.1 and 2. For example, the operations of method 2200 may be performed bythe UE auxiliary uplink manager as described herein. In some examples,the UE 115 may execute a set of codes to control the functional elementsof the device to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects the functions describedbelow using special-purpose hardware.

At block 2205, the UE 115 may receive an RRC message to configure the UEwith the CA configuration and the A-SRS configuration, where the RRCmessage includes A-SRS configurations for a set of UEs as describedabove with reference to FIGS. 2 through 5. In certain examples, theoperations of block 2205 may be performed by the configuration componentas described with reference to FIGS. 7 and 8.

At block 2210, the UE 115 may receive a resource assignment on a DLcarrier in the CA configuration as described above with reference toFIGS. 2 through 5. In certain examples, the operations of block 2210 maybe performed by the resource assignment component as described withreference to FIGS. 7 and 8.

At block 2215, the UE 115 may detect a trigger for transmitting an A-SRSbased on the resource assignment as described above with reference toFIGS. 2 through 5. In certain examples, the operations of block 2215 maybe performed by the A-SRS trigger component as described with referenceto FIGS. 7 and 8.

At block 2220, the UE 115 may determine UL resources of the A-SRSconfiguration for transmitting the A-SRS as described above withreference to FIGS. 2 through 5. In certain examples, the operations ofblock 2220 may be performed by the resource assignment component asdescribed with reference to FIGS. 7 and 8.

At block 2225, the UE 115 may transmit the A-SRS on the determined ULresources as described above with reference to FIGS. 2 through 5. Incertain examples, the operations of block 2225 may be performed by theA-SRS component as described with reference to FIGS. 7 and 8.

It should be noted that these methods describe possible implementation,and that the operations and the steps may be rearranged or otherwisemodified such that other implementations are possible. In some examples,aspects from two or more of the methods may be combined. For example,aspects of each of the methods may include steps or aspects of the othermethods, or other steps or techniques described herein. Thus, aspects ofthe disclosure may provide for A-SRS triggering for eCA.

The description herein is provided to enable a person skilled in the artto make or use the disclosure. Various modifications to the disclosurewill be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other variations withoutdeparting from the scope of the disclosure. Thus, the disclosure is notto be limited to the examples and designs described herein but is to beaccorded the broadest scope consistent with the principles and novelfeatures disclosed herein.

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different (physical)locations. Also, as used herein, including in the claims, “or” as usedin a list of items (for example, a list of items prefaced by a phrasesuch as “at least one of” or “one or more”) indicates an inclusive listsuch that, for example, a list of at least one of A, B, or C means A orB or C or AB or AC or BC or ABC (i.e., A and B and C).

Computer-readable media includes both non-transitory computer storagemedia and communication media including any medium that facilitatestransfer of a computer program from one place to another. Anon-transitory storage medium may be any available medium that can beaccessed by a general purpose or special purpose computer. By way ofexample, and not limitation, non-transitory computer-readable media cancomprise RAM, ROM, electrically erasable programmable read only memory(EEPROM), compact disk (CD) ROM or other optical disk storage, magneticdisk storage or other magnetic storage devices, or any othernon-transitory medium that can be used to carry or store desired programcode means in the form of instructions or data structures and that canbe accessed by a general-purpose or special-purpose computer, or ageneral-purpose or special-purpose processor. Also, any connection isproperly termed a computer-readable medium. For example, if the softwareis transmitted from a website, server, or other remote source using acoaxial cable, fiber optic cable, twisted pair, digital subscriber line(DSL), or wireless technologies such as infrared, radio, and microwave,then the coaxial cable, fiber optic cable, twisted pair, DSL, orwireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,include CD, laser disc, optical disc, digital versatile disc (DVD),floppy disk and Blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

Techniques described herein may be used for various wirelesscommunications systems such as CDMA, TDMA, FDMA, OFDMA, single carrierfrequency division multiple access (SC-FDMA), and other systems. Theterms “system” and “network” are often used interchangeably. A CDMAsystem may implement a radio technology such as CDMA2000, UniversalTerrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000, IS-95,and IS-856 standards. IS-2000 Releases 0 and A are commonly referred toas CDMA2000 1×, 1×, etc. IS-856 (TIA-856) is commonly referred to asCDMA2000 1×EV-DO, High Rate Packet Data (HRPD), etc. UTRA includesWideband CDMA (WCDMA) and other variants of CDMA. A TDMA system mayimplement a radio technology such as (Global System for Mobilecommunications (GSM)). An OFDMA system may implement a radio technologysuch as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE802.11, IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA andE-UTRA are part of Universal Mobile Telecommunications system (UniversalMobile Telecommunications System (UMTS)). 3GPP LTE and LTE-advanced(LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS,LTE, LTE-a, and GSM are described in documents from an organizationnamed “3rd Generation Partnership Project” (3GPP). CDMA2000 and UMB aredescribed in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). The techniques described herein may beused for the systems and radio technologies mentioned above as well asother systems and radio technologies. The description herein, however,describes an LTE system for purposes of example, and LTE terminology isused in much of the description above, although the techniques areapplicable beyond LTE applications.

In LTE/LTE-A networks, including networks described herein, the termevolved node B (eNB) may be generally used to describe the basestations. The wireless communications system or systems described hereinmay include a heterogeneous LTE/LTE-A network in which different typesof eNBs provide coverage for various geographical regions. For example,each eNB or base station may provide communication coverage for a macrocell, a small cell, or other types of cell. The term “cell” is a 3GPPterm that can be used to describe a base station, a carrier or componentcarrier (CC) associated with a base station, or a coverage area (e.g.,sector, etc.) of a carrier or base station, depending on context.

Base stations may include or may be referred to by those skilled in theart as a base transceiver station, a radio base station, an access point(AP), a radio transceiver, a NodeB, eNodeB (eNB), Home NodeB, a HomeeNodeB, or some other suitable terminology. The geographic coverage areafor a base station may be divided into sectors making up only a portionof the coverage area. The wireless communications system or systemsdescribed herein may include base stations of different types (e.g.,macro or small cell base stations). The UEs described herein may be ableto communicate with various types of base stations and network equipmentincluding macro eNBs, small cell eNBs, relay base stations, and thelike. There may be overlapping geographic coverage areas for differenttechnologies. In some cases, different coverage areas may be associatedwith different communication technologies. In some cases, the coveragearea for one communication technology may overlap with the coverage areaassociated with another technology. Different technologies may beassociated with the same base station, or with different base stations.

A macro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by UEswith service subscriptions with the network provider. A small cell is alower-powered base stations, as compared with a macro cell, that mayoperate in the same or different (e.g., licensed, unlicensed, etc.)frequency bands as macro cells. Small cells may include pico cells,femto cells, and micro cells according to various examples. A pico cell,for example, may cover a small geographic area and may allowunrestricted access by UEs with service subscriptions with the networkprovider. A femto cell may also cover a small geographic area (e.g., ahome) and may provide restricted access by UEs having an associationwith the femto cell (e.g., UEs in a closed subscriber group (CSG), UEsfor users in the home, and the like). An eNB for a macro cell may bereferred to as a macro eNB. An eNB for a small cell may be referred toas a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB maysupport one or multiple (e.g., two, three, four, and the like) cells(e.g., component carriers (CCs)). A UE may be able to communicate withvarious types of base stations and network equipment including macroeNBs, small cell eNBs, relay base stations, and the like.

The wireless communications system or systems described herein maysupport synchronous or asynchronous operation. For synchronousoperation, the base stations may have similar frame timing, andtransmissions from different base stations may be approximately alignedin time. For asynchronous operation, the base stations may havedifferent frame timing, and transmissions from different base stationsmay not be aligned in time. The techniques described herein may be usedfor either synchronous or asynchronous operations.

The DL transmissions described herein may also be called forward linktransmissions while the UL transmissions may also be called reverse linktransmissions. Each communication link described herein including, forexample, wireless communications system 100 and 200 of FIGS. 1 and 2 mayinclude one or more carriers, where each carrier may be a signal made upof multiple sub-carriers (e.g., waveform signals of differentfrequencies). Each modulated signal may be sent on a differentsub-carrier and may carry control information (e.g., reference signals,control channels, etc.), overhead information, user data, etc. Thecommunication links described herein (e.g., communication links 125 ofFIG. 1) may transmit bidirectional communications using frequencydivision duplex (FDD) (e.g., using paired spectrum resources) or timedivision duplex (TDD) operation (e.g., using unpaired spectrumresources). Frame structures may be defined for FDD (e.g., framestructure type 1) and TDD (e.g., frame structure type 2).

Thus, aspects of the disclosure may provide for A-SRS triggering foreCA. It should be noted that these methods describe possibleimplementations, and that the operations and the steps may be rearrangedor otherwise modified such that other implementations are possible. Insome examples, aspects from two or more of the methods may be combined.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a digital signal processor (DSP), an ASIC, anfield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration). Thus, the functions described herein may be performed byone or more other processing units (or cores), on at least oneintegrated circuit (IC). In various examples, different types of ICs maybe used (e.g., Structured/Platform ASICs, an FPGA, or anothersemi-custom IC), which may be programmed in any manner known in the art.The functions of each unit may also be implemented, in whole or in part,with instructions embodied in a memory, formatted to be executed by oneor more general or application-specific processors.

In the appended figures, similar components or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

What is claimed is:
 1. A method of wireless communication, comprising:receiving a resource assignment on a downlink (DL) component carrier(CC) in a carrier aggregation (CA) configuration, the resourceassignment comprising an identifier associated with aperiodic soundingreference signal (A-SRS) transmissions on one or more uplink (UL) CCs inthe CA configuration, and the resource assignment further comprisingpower control information for the A-SRS transmissions; detecting atrigger for the A-SRS transmissions based at least in part on theidentifier associated with the A-SRS transmissions; and transmitting theA-SRS transmissions on the one or more UL CCs in accordance with thepower control information and the detected trigger.
 2. The method ofclaim 1, wherein the identifier is a radio network temporary identifier(RNTI).
 3. The method of claim 2, wherein the RNTI is a soundingreference signal RNTI.
 4. The method of claim 1, wherein the one or moreUL CCs are configured to transmit A-SRS and not perform UL datatransmissions.
 5. The method of claim 4, wherein not performing UL datatransmissions comprises refraining from transmitting a physical uplinkshared channel (PUSCH) on the one or more UL CCs.
 6. The method of claim1, wherein receiving the resource assignment comprises: receiving adownlink control information format comprising the resource assignment.7. The method of claim 1, further comprising: determining, based atleast in part on a second identifier associated with A-SRStransmissions, that a second one or more A-SRS transmissions are not tobe transmitted; and transmitting a physical uplink control channel(PUCCH) transmission in accordance with the power control informationbased at least in part on determining that the second one or more A-SRStransmissions are not to be transmitted.
 8. The method of claim 7,further comprising: refraining, based at least in part on the secondidentifier, from transmitting the second one or more A-SRStransmissions.
 9. The method of claim 1, further comprising: determiningthat the identifier matches a predetermined combination of values,wherein the trigger is detected based at least in part on the matchedidentifier.
 10. The method of claim 1, further comprising: identifying agroup trigger from the resource assignment, the group trigger comprisingdata to specify the one or more UL CCs in the CA configuration that areto be used in transmitting the A-SRS transmissions, wherein thetransmission of the A-SRS transmissions is in accordance with theidentified group trigger.
 11. The method of claim 1, further comprising:identifying, based at least in part on the resource assignment, apattern for the transmission of the A-SRS transmissions, wherein theA-SRS transmissions are transmitted in accordance with the pattern. 12.An apparatus for wireless communication, comprising: a processor; memorycoupled with the processor; and instructions stored in the memory andexecutable by the processor to cause the apparatus to: receive aresource assignment on a downlink (DL) component carrier (CC) in acarrier aggregation (CA) configuration, the resource assignmentcomprising an identifier associated with aperiodic sounding referencesignal (A-SRS) transmissions on one or more uplink (UL) CCs in the CAconfiguration, and the resource assignment further comprising powercontrol information for the A-SRS transmissions; detect a trigger forthe A-SRS transmissions based at least in part on the identifierassociated with the A-SRS transmissions; and transmit the A-SRStransmissions on the one or more UL CCs in accordance with the powercontrol information and the detected trigger.
 13. The apparatus of claim12, wherein the identifier is a radio network temporary identifier(RNTI).
 14. The apparatus of claim 13, wherein the RNTI is a soundingreference signal RNTI.
 15. The apparatus of claim 12, wherein the one ormore UL CCs are configured to transmit A-SRS and not perform UL datatransmissions.
 16. The apparatus of claim 15, wherein not performing ULdata transmissions comprises refraining from transmitting a physicaluplink shared channel (PUSCH) on the one or more UL CCs.
 17. Theapparatus of claim 12, wherein the instructions to receive the resourceassignment are executable by the processor to cause the apparatus to:receive a downlink control information format comprising the resourceassignment.
 18. The apparatus of claim 12, wherein the instructions arefurther executable by the processor to cause the apparatus to:determine, based at least in part on a second identifier associated withA-SRS transmissions, that a second one or more A-SRS transmissions arenot to be transmitted; and transmit a physical uplink control channel(PUCCH) transmission in accordance with the power control informationbased at least in part on determining that the second one or more A-SRStransmissions are not to be transmitted.
 19. The apparatus of claim 18,wherein the instructions are further executable by the processor tocause the apparatus to: refrain, based at least in part on the secondidentifier, from transmitting the second one or more A-SRStransmissions.
 20. The apparatus of claim 12, wherein the instructionsare further executable by the processor to cause the apparatus to:determine that the identifier matches a predetermined combination ofvalues, wherein the trigger is detected based at least in part on thematched identifier.
 21. The apparatus of claim 12, wherein theinstructions are further executable by the processor to cause theapparatus to: identify a group trigger from the resource assignment, thegroup trigger comprising data to specify the one or more UL CCs in theCA configuration that are to be used in transmitting the A-SRStransmissions, wherein the transmission of the A-SRS transmissions is inaccordance with the identified group trigger.
 22. The apparatus of claim12, wherein the instructions are further executable by the processor tocause the apparatus to: identify, based at least in part on the resourceassignment, a pattern for the transmission of the A-SRS transmissions,wherein the A-SRS transmissions are transmitted in accordance with thepattern.
 23. An apparatus for wireless communication, comprising: meansfor receiving a resource assignment on a downlink (DL) component carrier(CC) in a carrier aggregation (CA) configuration, the resourceassignment comprising an identifier associated with aperiodic soundingreference signal (A-SRS) transmissions on one or more uplink (UL) CCs inthe CA configuration, and the resource assignment further comprisingpower control information for the A-SRS transmissions; means fordetecting a trigger for the A-SRS transmissions based at least in parton the identifier associated with the A-SRS transmissions; and means fortransmitting the A-SRS transmissions on the one or more UL CCs inaccordance with the power control information and the detected trigger.24. The apparatus of claim 23, wherein the identifier is a radio networktemporary identifier (RNTI).
 25. The apparatus of claim 24, wherein theRNTI is a sounding reference signal RNTI.
 26. The apparatus of claim 23,wherein the one or more UL CCs are configured to transmit A-SRS and notperform UL data transmissions.
 27. The apparatus of claim 26, whereinnot performing UL data transmissions comprises refraining fromtransmitting a physical uplink shared channel (PUSCH) on the one or moreUL CCs.
 28. The apparatus of claim 23, further comprising: means fordetermining, based at least in part on a second identifier associatedwith A-SRS transmissions, that a second one or more A-SRS transmissionsare not to be transmitted; and means for transmitting a physical uplinkcontrol channel (PUCCH) transmission in accordance with the powercontrol information based at least in part on determining that thesecond one or more A-SRS transmissions are not to be transmitted
 29. Theapparatus of claim 28, further comprising: means for refraining, basedat least in part on the second identifier, from transmitting the secondone or more A-SRS transmissions
 30. A non-transitory computer-readablemedium storing code for wireless communication, the code comprisinginstructions executable by a processor to: receive a resource assignmenton a downlink (DL) component carrier (CC) in a carrier aggregation (CA)configuration, the resource assignment comprising an identifierassociated with aperiodic sounding reference signal (A-SRS)transmissions on one or more uplink (UL) CCs in the CA configuration,and the resource assignment further comprising power control informationfor the A-SRS transmissions; detect a trigger for the A-SRStransmissions based at least in part on the identifier associated withthe A-SRS transmissions; and transmit the A-SRS transmissions on the oneor more UL CCs in accordance with the power control information and thedetected trigger.